Concept:Neutrons are neutral subatomic particles found in the nucleus, with mass nearly equal to that of a proton.
Explanation:Neutrons carry no electric charge and have a mass of
1.6750×10−27 kg.
They reside in the nucleus of every atom except hydrogen.
In 1932, James Chadwick discovered the neutron by bombarding beryllium with alpha particles.
Hence, the neutron was discovered by James Chadwick.
Note: Ernest Rutherford discovered the proton, J. J. Thomson discovered the electron, and John Dalton proposed atomic theory.
Answer:Option A – James Chadwick.